1. Field of the Invention
This invention relates to fire fighting equipment, and particularly to water nozzles adapted to pierce through a roof and provide a water spray to extinguish a fire, and to alternative, exchangeable embodiments that may pierce into other structures.
2. Background Information
Effective fire control and extinguishment requires basic understanding of chemical and physical nature of fire. Combustion is the rapid oxidation of fuel along with the evolution of heat and light. The xe2x80x9cfire trianglexe2x80x9d includes oxygen, heat and fuel; fire needs approximately 16% oxygen to free burn.
In its starting or xe2x80x9cincipient phase,xe2x80x9d fire may produce flame temperatures of 1000 degrees Fahrenheit, yet the room temperature is only slightly increased. Water vapor, carbon dioxide and small quantity of sulfur dioxide and carbon monoxide are present.
The second phase of fire is referred to as free burning; this encompasses all free burning activities of the fire. Oxygen rich air is drawn into the fire and convection heat carries gases into the uppermost regions of the room. The heated gases then spread out laterally from the upper most surfaces forcing the cooler air downward. Along its path fire is consuming all combustible materials and temperatures of approximately 1300 degrees Fahrenheit are consuming oxygen and will continue to burn until there is insufficient oxygen to react with the fuel load.
The third phase of fire, referred to as smoldering, occurs when the burning is reduced to glowing embers. If the room is sufficiently airtight and the oxygen has been reduced, temperatures will rise and smoke will fill the room along with increased hydrogen and methane gas which leads to the possibility of backdraft (a new entry of oxygen).
Early theories of fire fighting, often held even now by lay persons, were that the fire was to be xe2x80x9cdrowned,xe2x80x9d i.e., deprived of oxygen. The continuing development of the art, however, along with the contributions of physics and chemistry, have shown that the principal effect of applying fluids such as water to a fire lie in reducing the temperature below that at which burning will occur. That must occur, of course, by the transfer of heat energy from the burning materials to the water.
The processes by which water or similar such fire-fighting materials absorb heat are actually three in number: firstly, the water is heated up from its xe2x80x9chose temperaturexe2x80x9d to the boiling point; secondly, that heated water is vaporized into water vapor; and thirdly that water vapor is itself heated further, so long as the temperature of the fire remains above about 212 degrees Fahrenheit, the boiling point of water. It is the second one of those steps that is most effective in absorbing heat from a fire, as can be seen from a comparison of the number of calories or BTUs of heat required to accomplish each step.
Thus, the specific heat of water, by which is meant the amount of heat that is required to raise the temperature of a gram of water one degree Centigrade is approximately 1 calorie. The latent heat of vaporization of water, however, is 540 calories per gram. Since one BTU is equivalent to 252 calories, one gram of water can remove somewhat more than 2 BTU of heat from a fire by its vaporization alone. In more familiar firefighting terms, since a gallon of water weighs roughly 3.8 kilograms, vaporization of a gallon of water absorbs about 7,600 BTUs of heat.
The subsequent heating of the resultant water vapor is not inconsequential, given that the burning materials and hot gases may be 1000 degrees or so above room temperature, the object being, of course, that upon heating the water vapor the other materials will cool down below their ignition temperature and the fire will be extinguished. However, it is the initial vaporization of the incident water that makes the heating of the resultant water vapor possible, hence efficient water vaporization turns out to be the key step in effective fire-fighting.
The so-called xe2x80x9cexpansionxe2x80x9d of an amount of water into vapor is often referred to as being effective in xe2x80x9csmotheringxe2x80x9d a fire because that water vapor occupies space that might otherwise be occupied by oxygen. That idea, however, neglects the fact that even though the theoretical volume of an amount of water in the vapor state is about 1700 times that in its liquid state, one still has precisely the same amount of water, every molecule of water takes up roughly the same volume as it did in its liquid state, and since that water vapor now constitutes a gas, that theoretical volume consists primarily of empty space if the water vapor were there alone, or space that in the context of a fire will be filled with other gases, including both oxygen and the hot gases of the fire, such as the fire byproducts carbon monoxide and carbon dioxide. The effect of the dispersal of an amount of water into vapor derives not from any volume change, therefore, but rather because the wide dispersal of the water vapor puts it into intimate contact with the gases that are to be cooled off, and the same will of course be true of a mist of visible water droplets (which near the boiling point constitutes steam), and those droplets may then be vaporized into invisible water vapor to provide the most effective step in fire fighting.
Firefighters responding to a confined fire that is in either the free-burning or smoldering phases risk the occurrence of backdraft by ventilating the structure. The fire is incomplete because it has used up all available oxygen, yet heat has remained in the structure. Improper ventilation will increase oxygen which will then explode upon reaching the stalled combustion process. The proper use of the piercing nozzle and attachments will avoid opening up a new source of oxygen to remove one side of the fire triangle oxygen, and then by cooling the fire can be removed from its existing, dangerous state to one of extinguishment.
With respect to the cooling effects of mist, a test was conducted on one version of the mist-producing, penetrating nozzle to be described hereinafter, with reference to a standard fire nozzle that ejects liquid water. In a test building, fires were initiated in rooms of comparable size so as to become totally involved. Using a standard fire nozzle, the first of such fires was extinguished in 2 minutes using 250 gallons of water. The second fire was extinguished using the misting nozzle in 5 seconds using 15 gallons of water.
Generally representative of prior art penetrating nozzles is the xe2x80x9cFAAASTxe2x80x9d tool 10 manufactured and sold by Advanced Manufacturing Technologies, Inc. of Grafton, Wis. and shown in FIG. 1. Tool 10 generally comprises an elongate cylindrical and fluid-carrying shaft 12, at a first end of which is disposed a fluid discharge region 14 and distally therefrom a penetrating member 16. At a second end of shaft 12 is disposed firstly a nozzle connector 18 to which is attached a fluid-bearing fire hose (not shown), and secondly a guide shaft 20 for effecting orientation of tool 10 relative to a roof or like structure to be penetrated. Included on guide shaft 20 is a slide hammer 22 that can be used to assist in forcing the penetrating member 16 through a roof or the like. Particular nozzle tip designs can be seen in U.S. Des. 339,846 issued Sep. 28, 1993 to Magee and U.S. Des. 351,642 issued Oct. 18, 1994 to Mitchell.
Beyond such design considerations, some particular functional aspects of nozzle construction have been set out in U.S. Pat. No. 4,358,058 issued is Nov. 9, 1982 to Bierman, U.S. Pat. No. 4,700,894 issued Oct. 20, 1987 to Grzych, and U.S. Pat. No. 4,568,025 issued Feb. 4, 1986 to McLoud. The Bierman device includes a rotating section and control handle whereby an operator can select among modes of operation involving a whirling wide angle cone of fog, a forward narrow angle cone of fog, a solid stream, or shutoff. The Grzych device provides an essentially spherical stream of fog so as to encompass the entire interior of a room, thus also eliminating reactive forces that can give rise to whipping. The McLoud device provides a downwardly directed cone of spray over a developed fire. Although the Bierman, Grzych and McLoud devices each permit extension of their respective nozzles into a room while the operator remains outside, none provides means for piercing or penetrating into such a room using the nozzle itself.
Additional variations in nozzle design include U.S. Pat. No. 5,261,494 and 5,447,203, respectively issued Nov. 16, 1993, and Sep. 5, 1995, to McLoughlin et al., which provide means for independent control of both a solid stream of water for xe2x80x9cpunchingxe2x80x9d into a fire and a fog-generating mode for cooling a larger region of a fire, provision also being made for remote control operation, a later version in U.S. Pat. No. 5,590,719 issued Jan. 7, 1997 to McLaughlin et al. that includes a foam injection system, and U.S. Pat. No. 5,277,256 issued Jan. 11, 1994 to Bailey that provides for switching between the dispensing of water in the usual manner, or of two other firefighting agents. Similarly, U.S. Pat. No. 5,678,766 issued Oct. 21, 1997 to Peck et al. provides for discharging a foam and water mixture. However, these are again not penetrating or piercing nozzles.
One rather unique such device that is particularly adapted to fighting fires that have developed within the xe2x80x9cinsulation spacexe2x80x9d of a wall is described in U.S. Pat. No. 4,485,877 issued Dec. 4, 1984 to McMillan et al. This device includes a penetration member that is relatively smaller than and mounted transversely to the main fluid conduit, provision being made for diversion of fluid into that penetration member so as to be discharged within a wall into which the penetration member has been forced. An additional safety feature is that when the device is used instead in its usual xe2x80x9cattackxe2x80x9d mode employing the main fluid conduit, the spraying feature of the penetration means can be activated as well so as to provide a protective ball of mist in the vicinity of the operator. By contrast, and similar to the device of FIG. 1, however, in most cases the piercing or penetrating feature of fire nozzles has been incorporated within the main fluid dispensing nozzle.
As to such specifically penetrating nozzles, U.S. Pat. No. 4,697,740 issued Oct. 6, 1987 to Ivy describes a device similar to that shown in FIG. 1 except that instead of using a slide hammer to assist in forcing the nozzle through a roof or similar obstacle, the end of the fluid conduit opposite the nozzle terminates in a strike plate that may be directly hammered upon so as to force penetration. The channel through which the fluid to be dispensed arrives at that fluid conduit is then connected into the side of that conduit, at an angle so as to trail off away from the nozzle end. A patent that shows the slide hammer of FIG. 1 is found in U.S. Pat. No. 5,062,486 issued Nov. 5, 1991 to McClenahan, but which is distinguished from both the device of FIG. 1 and the Ivy device by having a penetrating member that is symmetrical about a central axis, while the penetrating members of FIG. 1 and of Ivy have an elliptically bevelled structure, yielding a sharp and curved edge to facilitate penetration.
Another feature of the Ivy device, also found in a different form in U.S. Pat. No. 5,253,716 issued Oct. 19, 1993 to Mitchell, involves the use of orifices for the discharge of water or other fire suppression agents that breaks the agent into small droplets or xe2x80x9cmistxe2x80x9d for more effective fire suppression, i.e., water configured into droplets rather than as a solid stream presents a much larger surface area for absorption of heat from the fire, those droplets convert to steam thus absorbing even more heat, and both the droplets and steam encompasses a larger volume to assist in excluding oxygen. The mechanism for so doing in Ivy comprises an internal cylinder including elongate slots, and externally adjacent to that cylinder a sleeve bearing a plurality of small apertures. Ejection of water through such apertures causes the sleeve to rotate, thereby momentarily exposing those apertures to the adjacent slots so as to discharge the fluid outwardly therefrom in a spiral pattern of droplets. The piercing member is connected by matching threads to the main fluid-bearing shaft.
In the Mitchell device, which incorporates a tetrahedral (or xe2x80x9cbayonetxe2x80x9d) rather than a bevelled penetration member, a mist is formed by the use of pairs of small fluid discharge apertures set at relative angles of ninety degrees which causes collision between emerging streams of such agents thereby breaking those streams into droplets. The Mitchell device also has a modular construction to permit being carried in segments that can be locked together at the time of use, wherein the total resultant length of the device can be selected so as to be convenient within the space available at a particular fire scene.
The aforesaid devices exploit generally the processes of penetrating building structures so as to bring to bear therein a fire extinguishing medium, and secondly of providing that medium (typically water) in a misted or fogged form so as to extinguish a fire more efficiently. Improvement of such devices with respect both to the patterns of mist or fog that are to be generated and the structures that may be penetrated are then the subject matter of the present invention, particularly with respect to providing the ability to accommodate a variety of fire-fighting situations using a single tool. What is needed and would be useful, therefore, are added means for protection of the fire-fighter, easier penetration of the structure to be treated, and flexibility both as to convenient, on-site adaptation of the tool to the nature of the structure within which a fire is to be extinguished, including automobiles and boats and the like, and some means for adapting the fluid pattern to be applied to the nature and disposition of the fire within some particular type of structure, as will be hereinafter shown and described.
The invention is a fire-fighting tool incorporating a ceramic thermal barrier for user safety, a non-slip grip and doubly bevelled penetration member for ease of use, an array of interchangeable nozzle wands for use in a variety of fire-fighting situations, and improved mist-producing means whereby the mist can be formed in pre-determined patterns and be directed at pre-determined angles from the tool so as better to attack the specific location and type of fire within various structures.